KDNBF (potassium 4,6-dinitrobenzofuroxan) has been used as a primer explosive in igniters and detonators for many years. Considerable
information about the sensitivity of KDNBF to various stimuli, such as impact, friction, shock and electrostatic charge, is
known. However, the thermal sensitivity of KDNBF has been relatively unexplored. Hence, there is very little information available
concerning the fundamental thermal properties of KDNBF. Therefore, as part of an extensive thermal hazard assessment, DSC,
TG, accelerating rate calorimetry (ARC) and heat flux calorimetry (HFC) measurements have been undertaken on KDNBF. The results
demonstrate that KDNBF decomposes via a multi-step exothermic process directly from the solid state. The decomposition process
does not appear to depend on the nature of the atmosphere, except in the final stage of the TG decomposition in air, where
remaining carbonaceous material is converted to CO2. The first stage of the decomposition is sufficiently rapid that ignition occurs if too large a sample is used. Dynamic and
isothermal methods were used to obtain the kinetic parameters and a range of activation energies were obtained, depending
on the experimental conditions. The kinetic results have been analyzed in terms of various solid state decomposition models.
Authors:D. Jones, H. Feng, R. Augsten and R. Fouchard
Isopropylnitrate (IPN) is described as a detonable material used in propellants and explosives. While there is considerable
information available on its sensitivity and compatibility with other materials, very little is known about its thermochemical
properties. This paper will describe the results obtained from some DSC, heat flux calorimetry (HFC) and accelerating rate
calorimetry (ARC) measurements.
The ASTM DSC method using a hermetic aluminum pan having a lid with a laser-produced pin hole was used to determine the vapour
pressure of IPN1. Results calculated from an Antoine equation are in substantial agreement with those determined from DSC measurements. From
the latter measurements, the enthalpy of vaporization was determined to be 35.320.62 kJ mol−1. Attempts to determine vapour pressures above about 0.8 MPa resulted in significant decomposition of IPNg.
The enthalpy change for decomposition in sealed glass systems was found to be -3.430.09 kJ g−1 and -3.850.03 kJ g−1, respectively from DSC and HFC measurements on IPN1 samples loaded in air. Slightly larger exotherms were observed for the HFC results in air than those in inert gas, suggesting
some oxidation occurs. In contrast, no significant difference in the observed onset temperature of about 150C was observed
for both the HFC and ARC results.
From DSC measurements, an Arrhenius activation energy for decomposition of 1264 kJ mol−1 was found. These measurements were also conducted in sealed glass systems and decomposition appeared to proceed primarily
from the liquid phase.
Authors:R. Turcotte, R. Fouchard, A.-M. Turcotte and D. Jones
While there is abundant literature describing the factors affecting the performance and the mechanical sensitivity of black
powder, only a few papers are devoted to its thermal properties. Previous work indicated that no exothermic reactions were
observed below 300C in an inert gas environment. In the present work a variety of thermal techniques (DSC, TG, simultaneous
TG-DTA-FTIR-MS, ARC, HFC) has been used to study the thermal decomposition of black powder. Exothermic reactions were observed
at temperatures as low as 230 and 140C in inert and oxidizing atmospheres, respectively. The latter exothermic reaction is
due to sulfur oxidation.
Authors:D. Jones, P. Brousseau, R. Fouchard, A. Turcotte and Q. Kwok
The thermal properties of Alex, a nanosized Al powder, were determined using various techniques, including DSC, TG, simultaneous
TG-DTA (SDT) and accelerating rate calorimetry (ARC). The results demonstrate that the specific heat capacities of nano and
micron size Al powders are similar between 30 and 400C. Dynamic and isothermal methods were used to determine the kinetic
parameters for the oxidation reaction of Alex, which was detected at an onset temperature of 481C. The results obtained were
in good agreement with each other. From the ARC experiments, exotherms were detected near 340 and 260C for experiments started
at ambient pressure and at 0.72 MPa, respectively.